How did you get that smile.

Orthodontic appliances, mouth jewelry -- no matter what you call them, braces fill your mouth with gadgets. But they also use some basic physics to give you a better smile.

Here's the straight story on braces.

Buccal tubes are welded onto metal bands. The tubes have slots that hold arch wires, elastics, and other gadgets that help move teeth.

Rubber bands hooked to metal bands and brackets align the upper and lower jaws. Users must change the bands twice a day. Those who have trouble keeping to the routine can opt for metal springs that do the same job -- but never have to be changed.

Ceramic brackets are bonded to the front of the teeth. A new adhesive releases fluoride to protect the enamel under the brackets and prevent tooth decay.

Metal bands are cemented only onto molars, or back teeth. Metal bands serve as anchors for other corrective devices, such as brackets and springs.

Arch wire applies force to pull teeth to their proper positions. The orthodontist threads the wire through slots in the brackets. Small elastics hold the wire in place.